Endoscopes are used today for a number of applications in medicine and technology. Endoscopes typically include a rigid or flexible longitudinally extended shaft that is suitable for insertion into a cavity and on whose point an endoscope object lens is positioned to generate an image of a scene in the observed cavity. To record and retransmit the endoscopic image from the distal (that is, removed from the observer) end of the endoscope to the proximal end (close to the observer), it is possible for example to foresee an arranged bundle of light conductor fibers inside the shaft or an electronic image recorder, for example a CCD chip, in the area of the distal end of the shaft as well as electric lines inside the shaft. For rigid endoscopes, lens systems that can include a number of rod lenses can also be used to retransmit the image. Because sufficient light is usually not available as a rule in the observed cavity, a light conductor system is also foreseen inside the shaft in order to transport sufficient light to the distal end of the endoscope where it is used to illuminate the cavity.
In a number of applications it is desirable to be able to bend the distal end of the endoscope shaft, that is, the endoscope tip, to be able to modify not only the alignment of the endoscope tip but also the viewing angle of a lens positioned in the endoscope tip. Thus, for example in gastroscopy, sigmoidoscopy or bronchoscopy, use is made of endoscopes in which the shaft is configured to be flexible at least for a great part of its length and the endoscopic tip can be displaced to facilitate insertion of the endoscope into the cavity and to adjust the viewing angle to the particular requirements. For similar reasons, in the industrial field as well it is possible to use endoscopes with a long, flexible shaft, for example in investigating larger machinery with complex internal spaces such as turbines or combustion chambers.
In laparoscopy as well, a bendable endoscopic tip can be advantageous. Thus the restricted working area, as determined by the gas-filled abdomen in endoscopic operations, can be observed more comfortably with an endoscope whose tip is bendable. For this purpose, a short endoscopic tip, which can be bent at a large angle, is particularly advantageous. It can take the form, for example, of the tip of an endoscope with an otherwise rigid shaft.
To displace the bendable endoscope tip, it can be controlled by an operator, possibly along with other portions of the flexible endoscope shaft, from the proximal end of the endoscope.
To allow controllable bending of part of a flexible endoscope shaft, it is standard in the art to configure said shaft with a base structure made up of individual segments that can be pivoted with respect to one another. Thus, for example from DE 10 2007 001 580 A1, it is known that successive segments can be connected with one another by a single-axis pivot joint in each case and can be displaced at a small angle with respect to one another. According to U.S. Pat. No. 6,780,151 B2, a number of solid-state joints are aligned along the shaft. To displace the entire shaft or else the endoscope tip, tractive cables are provided that are fed through the endoscope as far as an actuating device located in the handle. Here every segment can be pivoted by a small angle with respect to the preceding or succeeding one. Bending by a large angle, for example 45 or 90 degrees, therefore requires a number of such segments and thus a relatively long endoscope tip, and thus it becomes impossible to use this endoscope in applications in which a small bending radius is necessary. In addition, in the bending process the individual segments mutually influence one another. If it is possible to bend only within a plane, then in order to be able to observe the entire space the shaft of the endoscope must be turned on its longitudinal axis; however, in the process the image recorded by the video camera turns correspondingly along with it, making orientation in the cavity difficult for the operator. If, on the other hand, a bending in several planes becomes possible by alternately rotated pivot axes by 90 degrees in each case, then this requires twice the number of segments, leading to a still greater minimum bending radius.
Patent US 2005/0131279 A1 discloses an endoscope shaft in which every segment allows a displacement around two axes that are perpendicular to one another, relative to the succeeding or preceding segment. Here too, however, the angle of displacement is relatively small, and therefore a small bend radius of the shaft or of the tip is not possible. According to US 2008/0027285 A1, segments of the shaft of an endoscope are connected together by several flexible connecting sections made up of spiral springs, such that the connecting sections can be bent in several planes with the help of cable pulls. Because of the flexibility of the connecting sections, however, an unintended displacement of the endoscope segments with respect to one another can occur. In addition, as a result of the tractive force there can be a change in length at an angle, impeding operating ability, along with an abrasion of the cable pulls.
U.S. Pat. No. 6,036,636 discloses an endoscope with a bendable tip, wherein the tip is connected with the endoscope shaft by a number of wires, so that bending of the tip can be accomplished by sliding the wires in relation to one another. The endoscope contains at least one elastic wire around which the endoscope tip can be bent, and at least one elastic pull or push wire with which the endoscope tip can be bent at an angle. Depending on the number of wires, the tip of the endoscope can be bent in all directions. In the process, because of the strong bending of the wires and the considerable pressure in bending, there is a danger of wearing out the material or breaking it, especially with large bending angles.
Patent US 2009/0171154 A1 discloses an endoscope whose distal end is bent by having an inner part of the endoscope extended with respect to the outer shaft, the outer shaft and the bendable tip being connected with one another by a strap. As a result, bending can occur only in one plane and in one direction.
According to patent DE 299 07 430 U1, a prism combination is positioned on the distal end of a rigid endoscope shaft, and in said prism combination the optical axis is deflected twice by 90 degrees each time. By means of a rotary mechanism the prisms are turned by 360 degrees to produce a desired viewing angle. In the process, however, complex mechanics are required for the displacement, and in addition the entire outer diameter of the shaft is increased, restricting the range of possible applications.